Quirks & Quarks

How Mercury is Getting into Arctic Caribou

The source of elevated levels of Mercury in caribou seems to be lichen absorbing mercury pollution from the south that is off-gassing from nearby sea-water.

Contamination of Arctic land animals is coming from the sea

Caribou grazing on an Arctic shoreline (Martin Fortier)
Mercury pollution from industrial sources tends to accumulate in Arctic waters, and has been known to bio-concentrate in the marine food chain, to the detriment of marine predators and Arctic peoples. But mercury has also found its way into caribou and the terrestrial food chain, and just how it has done so has been somewhat mysterious.

Now, Kyra St. Pierre and her colleagues have found that, in a complex chain of circumstances, bacteria are releasing mercury into the air near coastal locations, where lichen are filtering it from the air, and then caribou are eating the contaminated lichen.

Levels in caribou (and lichen) are low, and not a public health concern, but with increasing temperatures and decreasing ice in the Arctic, it's possible more mercury could make its way onto the land.

Related Links

- Paper in Environmental Science and Technology
- University of Alberta release